Mothers Who Breastfeed Might Have Lower Multiple Sclerosis Risk

(Reuters Health) - Women who breastfeed may have a lower risk of developing multiple sclerosis later in life compared to mothers who don’t nurse their infants, a recent U.S. study suggests.

Multiple sclerosis (MS) is a rare, disabling autoimmune disease that damages the central nervous system and predominantly develops in women of childbearing age. It can lead to fatigue, pain, vision loss and impaired coordination and motor skills.

For the current study, researchers examined data on total breastfeeding duration after all pregnancies for 397 mothers newly diagnosed with MS or a precursor condition and a control group of 433 mothers who were similar in age, race, income, education and smoking history who didn’t have MS.

Compared with women who breastfed for a total of no more than four months, mothers who nursed babies for at least 15 months were 53 percent less likely to develop MS, the study found.

“This study opens up the possibility that along with reducing the risk of heart disease, diabetes, ovarian and breast cancer, breastfeeding particularly for longer durations may also reduce the risk of multiple sclerosis and possibly other autoimmune diseases,” said lead study author Dr. Annette Langer-Gould, a neurology researcher with Kaiser Permanente in Pasadena, California.

Why breastfeeding might reduce the risk of MS is unclear.

One theory is that shifts in sex hormone levels with pregnancy and breastfeeding might play a role, and another possible explanation is that a lack of ovulation might play a role, researchers note in the journal Neurology.

To test these ideas, researchers looked at the total number of years women spent ovulating based on the age they began menstruating, the total time they spent pregnant or nursing, and in some cases their age at menopause.

They didn’t find an association between the duration of ovulation and the risk of developing MS, however. The number of pregnancies, use of hormonal contraceptives, and the age women gave birth for the first time also didn’t appear to influence the odds of getting MS.

Starting menstruation at a younger age did appear to raise risk. Women who were 15 or older when they got their first period were 44 percent less likely to develop MS as women who were 11 or younger when they began menstruating, the study found.

Overall, 85 women without MS breastfed for at least 15 months, compared to just 44 of the mothers with MS.

In contrast, 110 women without MS breastfed for no more than four months, compared to 118 women with MS.

The study wasn’t a controlled experiment designed to prove whether or how breastfeeding might protect against MS. Other limitations include the lack of data on why some women didn’t breastfeed at all or did so only for a few months, the authors note.

Breastfeeding might curb the risk of MS by reducing pro-inflammatory activity, however, this area has not been carefully studied by basic scientists,” Langer-Gould said by email.

Because very few women who choose to breastfeed are unable to do it for biological reasons, it’s unlikely that an inability to produce milk would explain the study findings, Langer-Gould added.

“It is possible that women who choose to breastfeed, particularly for longer durations, lead an overall healthier lifestyle and that another aspect of a healthy lifestyle that we did not measure could explain these findings,” she said.

“Even if the reasons aren’t yet clear, the study strengthens the body of evidence suggesting that breastfeeding influences MS, said Dr. Patricia Coyle, director of the MS Comprehensive Care Center Stony Brook University Medical Center in New York.

“This is further evidence of a potential benefit of breastfeeding: to avoid future immune mediated disease,” Coyle, who wasn’t involved in the study, said by email. “But most important is trying to understand why breastfeeding has this impact on MS risk.”